Flexographic printing is a letterpress technique using flexible plates, commonly used today for printing various paper-based carriers such as bags or packing cases, wallpaper intended for covering walls, serviettes and tablecloths, envelopes, etc . . . Flexographic printing can be mono- or polychrome and it preferably uses water-based inks in order to eliminate the pollution produced by the organic solvents of traditional inks. The use of water-based inks is often incompatible with high productivity and good quality printing because on traditional paper carriers, these water-based inks have a tendency to bleed, run, and smudge and furthermore, they take a long time to dry. Therefore a coating process is sought which would provide paper capable of being flexographically printed with water-based inks without causing bleeding and/or running, whilst providing a high productivity. In order to do this, either the use of special inks, or modification of the state of the paper surface have been proposed. Amongst these modifications, there can be mentioned notably treatment with wetting agents, the use of special adjuvants such as hydrosoluble polymers, special refining of the printer's pie, use of special fillers, etc . . .
These various modifications do not however permit good quality flexographic printing with high productivity and a low cost. In order to respond to the more and more drastic demands of the market, the Applicant has discovered a new coating process for papers intended to be flexographically printed allowing high printing rates, at a low cost without causing smudging, running and/or penetration.